A recent update to Canon's Japanese website titled "Apology and guidance regarding product supply status" states that as a result of the large volume of orders and "due to the influence of global parts supply, delivery delays are occurring."
The Canon EOS R3, along with the RF 14-35mm F4 lens, have listed shipping delays of up to six months after you place your order. Canon says that it is working on stabilizing its supply chain to deliver products as soon as possible (via CanonRumors).
The Canon EOS R3 was released in November 2021 and features a 24MP Full-Frame Sensor, Dual Pixel CMOS autofocus, EYE Control AF, 5-Axis in-body stabilization, and the ability to shoot in 6K/60 RAW and 4K at up to 120 frames per second. It seems to fall nicely between the Canon R5 series and the Canon EOS R while having Flagship Canon 1DX Mark III vibes.
Supply chain shortages are common since the beginning of the Covid-19 pandemic, causing product delays across many industries, with tech giants unable to meet consumer demand.
We will keep you updated if there are any changes or announcements from Canon.